With increasing miniaturization, micromilling is gaining importance due to its capability to manufacture complex microstructures with high surface quality using five-axis machining. However, the use of difficult-to-machine tool steels for the production of wear-resistant components limits the potential of micromilling. This is primarily due to high tool loads, which result in rapid tool wear. The reduced tool life of micromilling tools consequently limits both productivity and achievable surface quality. This highlights the need for innovative strategies for the micromachining of high-performance materials. A promising development is the use of hybridized, thermally assisted micromilling processes. These processes aim to induce thermal softening of the workpiece material through controlled heating, thereby reducing the required process forces. Laser-assisted machining is particularly noteworthy, as it introduces extremely high temperatures locally into the workpiece surface. However, the concentrated heat-affected zones and the unfavorable influence on the surface-near material are disadvantageous, as they can negatively affect fatigue properties. Against this background, the proposed research focuses on an alternative hybridization approach for micromilling. This approach aims to achieve complete and homogeneous heating of small workpieces in order to provide controlled, workpiece-friendly process assistance with a high degree of process flexibility. Particular emphasis is placed on improving the machining of hardened steels.

Preliminary investigations demonstrate the effectiveness of the selected process assistance (Fig. 1), which temporarily and selectively thermally softens the workpiece material, resulting in a significant reduction in cutting forces, tool wear, and burr formation. The objective of the project is to identify and evaluate the boundary conditions, potential, and optimized process windows for thermally assisted micromilling of various steel materials and to consolidate the findings into an efficient process strategy. To this end, a demonstrator device for the homogeneous heating of machining specimens will be further developed, incorporating efficient insulation mechanisms. Based on experimental investigations, a comprehensive understanding of the influence of specimen temperature on the machining process will be established in order to optimize key process factors with regard to increased productivity.

Literature

Platt, T.; Meijer, A.; Biermann, D. Conduction-Based Thermally Assisted Micromilling Process for Cutting Difficult-to-Machine Materials. J. Manuf. Mater. Process. 2020, 4, 34. [CrossRef]